A standard two-part cap for a recipient, hereinafter referred to as a bottle, typically has a plug of cork or thick plastic material that is inserted in the neck of the bottle, and a collar or sleeve surrounding this plug and the neck of the bottle. Once the bottle is filled, the plug is fitted in place, and then the sleeve is fitted around the neck. Such an arrangement can form the sleeve by coating the plugged neck of the bottle in a material that hardens to form the sleeve or as described in French Pat. No. 2,560,156 of Gerard Delval and U.S. Pat. No. 4,497,156 by shrinking the sleeve in place.
When the neck of the bottle has a thread so that the cap is replaceable, it is standard practice to form the sleeve of an aluminum foil that is pressed against the neck so as to shape the threads in it. Although fairly weak and rather expensive to manufacture, such a cap can be reused several times before the threads give out.